Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 250900
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
300 AM MDT MON JUL 25 2016

.SHORT TERM...Today Through Tuesday Night
Issued at 256 AM MDT Mon Jul 25 2016

Upper ridging over northern Rockies-plains will flatten as
several short waves track eastward. Strongest wave currently over
sern WA-nern OR will move into MT-WY this afternoon. As surface
high pressure over OMA vicinity continues to move southward, lee
trof deepens across MT, with southerly winds increasing over
forecast area today. Thunderstorm initiation will begin over the
northern Black Hills around noon as CAPE rapidly increases to 2000
j/kg and cap dissipates. Theta-E ridge builds over western SD/far
NE WY during the afternoon, indicating additional thunderstorm
development over northwestern SD. Strongest CAPE and Theta-E axis
shifts eastward overnight, and coupled with the low level jet
expect thunderstorms to continue eastward after midnight.

Surface low develops along the trof in the vicinity of the Black
Hills-eastern WY Tuesday with a warm front extending to the east.
Much larger area of CAPE > 3000 j/kg and broader Theta-E ridge
ahead of low indicates more widespread storms and more likely severe
storms.

temperatures build back into the 90s today and Tuesday.

.LONG TERM...(Wednesday Through Sunday)
Issued at 256 AM MDT Mon Jul 25 2016

Following a backdoor cool front, highs Wednesday will be closer
to seasonal averages, in the 80s. Easterly surface winds will
advect in moist air, with dew points across the western SD plains
in the 60s. MLCAPE near 2000 J/kg is progged across western SD
even in the early morning hours, and 0-6 km shear will be
sufficient for supercells. Meanwhile, a shortwave is expected to
cross the area during the day. Therefore, another round of
thunderstorms is expected for Wednesday, some of which may be
severe.

Chances for showers and thunderstorms continue Thursday and Friday
as the active pattern persists. Then an upper ridge moves over the
region, with warmer and drier weather expected for the weekend.

&&

.AVIATION...For the 12Z TAFS Through 12Z Monday Night
Issued At 256 AM MDT Mon Jul 25 2016

VFR conditions will continue through this morning. Scattered
strong to severe thunderstorms will develop during the afternoon
and evening, especially over the Black Hills and western SD. MVFR
to IFR visiblities are possible near storms.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

SHORT TERM...55
LONG TERM...Pojorlie
AVIATION...Pojorlie



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